test: deflake connect-timeout watchdog

[mcollina]

Summary

• deflake the connect-timeout tests by using a shared helper for Client and Pool
• replace the aggressive 2s watchdog with a longer guard that matches FastTimer behavior and the extra Windows setImmediate hop
• use test-scoped cleanup that tolerates an already-closed dispatcher

Testing

• npx borp -p "test/connect-timeout.js"
• npx eslint test/connect-timeout.js

Closes #5187

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.22%. Comparing base (f14c445) to head (74c219a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5197      +/-   ##
==========================================
- Coverage   93.23%   93.22%   -0.01%     
==========================================
  Files         110      110              
  Lines       36599    36599              
==========================================
- Hits        34122    34119       -3     
- Misses       2477     2480       +3     

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[metcoder95]

merge conflicts

[metcoder95]

Suggested change

	clearTimeout(timeout)
	resolve()
	} catch (error) {
	clearTimeout(timeout)
	reject(error)
	}
	resolve()
	} catch (error) {
	reject(error)
	} finally {
	clearTimeout(timeout)
	}